Hamiltonian simulation of the Schwinger model at finite temperature

TL;DR

This paper employs Matrix Product Operators to simulate the Schwinger model at finite temperature, computing thermal properties, probing string tension with fractional charges, and examining symmetry restoration, thus advancing quantum simulation techniques for gauge theories.

Contribution

It introduces a variational MPO approach for gauge-invariant thermal states and applies it to study finite-temperature phenomena in the Schwinger model, including string tension suppression and symmetry restoration.

Findings

Agreement with previous studies on chiral condensate

Identification of a critical temperature for string tension suppression

Evidence for CT symmetry restoration at nonzero temperature

Abstract

Using Matrix Product Operators (MPO) the Schwinger model is simulated in thermal equilibrium. The variational manifold of gauge invariant MPO is constructed to represent Gibbs states. As a first application the chiral condensate in thermal equilibrium is computed and agreement with earlier studies is found. Furthermore, as a new application the Schwinger model is probed with a fractional charged static quark-antiquark pair separated infinitely far from each other. A critical temperature beyond which the string tension is exponentially suppressed is found, which is in qualitative agreement with analytical studies in the strong coupling limit. Finally, the CT symmetry breaking is investigated and our results strongly suggest that the symmetry is restored at any nonzero temperature.